1. Field of the Invention
The invention resides in the field of optical spectrometers and more particularly relates to apparatus for producing, augmenting and enhancing the sample excitation situs or light source to be analyzed by those spectrometers.
2. Description of the Prior Art
Direct current arcs, plasmas, flames and other means of sample atomic excitation are commonly used for the purpose of spectral analysis. In many cases, these light or excitation sources are used in multi-element analysis systems, i.e., systems where the presence of more than one element is detected at a single time. One of the difficulties encountered in these systems relates to the spatial separation within the light source region of emissions from atomic transitions of varying excitation energy. In general, these will be separated according to the spatial temperature profile of the excitation source employed, the highest temperatures yielding the highest energies. As a result, information anomalies can occur when a variety of elements are present with excitation profiles which overlap. This often requires a difficult compromise when selecting which area of the situs or source to focus on the input aperture of the analyzing spectrometer.
In the invention described herein, the sample excitation situs or light source may be focused on the spectrometer input aperture in the conventional manner using a lens or mirror. In addition, a mirror is placed on the opposite side of the excitation situs from the spectrometer aperture such that an image of the excitation situs is reflected in close proximity upon itself. The mirror may be arranged to reverse the image yielding the reverse of the temperature, and therefore excitation energy profile, resulting in an effective averaging and enhancement of the intensity profile.
Additionally, this image may be shifted along the vertical or longitudinal axis of the original situs in order to emphasize one region of the source or another. Further, by positioning the image in front of or in back of the central plane of the situs, it is possible to compensate for the chromatic effects of any lenses which may be used to focus the source on the spectrometer aperture.
An additional advantage of this procedure of imaging is a substantial increase in the energy input into the spectrometer.
The inventor knows of no other apparatus or arrangement disclosed in the prior art which will accomplish the purposes and advantages of the invention as described above.